Difficult Mask Ventilation

Department of Anesthesiology-West, Medical College of Wisconsin, Froedtert Memorial Lutheran Hospital, 9200 W Wisconsin Ave., Milwaukee, WI 53226, USA.
Anesthesia and analgesia (Impact Factor: 3.47). 12/2009; 109(6):1870-80. DOI: 10.1213/ANE.0b013e3181b5881c
Source: PubMed


Mask ventilation is the most fundamental skill in airway management. In this review, we summarize the current knowledge about difficult mask ventilation (DMV) situations. Various definitions for DMV have been used in the literature. The lack of a precise standard definition creates a problem for studies on DMV and causes confusion in data communication and comparisons. DMV develops because of multiple factors that are technique related and/or airway related. Frequently, the pathogenesis involves a combination of these factors interacting to cause the final clinical picture. The reported incidence of DMV varies widely (from 0.08% to 15%) depending on the criteria used for its definition. Obesity, age older than 55 yr, history of snoring, lack of teeth, the presence of a beard, Mallampati Class III or IV, and abnormal mandibular protrusion test are all independent predictors of DMV. These signs should, therefore, be recognized and documented during the preoperative evaluation. DMV can be even more challenging in infants and children, because they develop hypoxemia much faster than adults. Finally, difficult tracheal intubation is more frequent in patients who experience DMV, and thus, clinicians should be familiar with the corrective measures and management options when faced with a challenging, difficult, or impossible mask ventilation situation.

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    • "Mask ventilation as an initial ventilation support is widely used for unconscious subjects either in an emergency or during induction of general anesthesia [1]. About 250,000 cases of cardiac arrest annually occur outside of hospitals, and 370,000 to 750,000 cases occur in hospitals [2,3]. "
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    ABSTRACT: Upper airway obstruction (UAO) is a major problem in unconscious subjects making full face mask ventilation difficult. The mechanism of UAO in unconscious subjects shares many similarities with that of obstructive sleep apnea (OSA), especially the hypotonic upper airway seen during rapid eye movement sleep. Continuous positive airway pressure (CPAP) via nasal mask is more effective at maintaining airway patency than a full face mask in OSA patients. We hypothesized that CPAP via nasal mask and ventilation (nCPAP) would be more effective than full face mask CPAP and ventilation (FmCPAP) for unconsciousness subjects and we tested our hypothesis during induction of general anesthesia for elective surgery. A total of 73 adult subjects requiring general anesthesia were randomly assigned into four groups: nCPAP P0, nCPAP P5, FmCPAP P0, and FmCPAP P5, where P0 and P5 represent positive end expiratory pressure (PEEP) 0 and 5 cmH2O applied prior to induction. After apnea, ventilation was initiated with pressure control ventilation at a peak inspiratory pressure over PEEP (PIP/PEEP) of 20/0, then 20/5 and finally 20/10 cmH2O each applied for 1 min. At each pressure setting, expired tidal volume (Vte) was calculated using a plethysmograph device. The rate of effective tidal volume (Vte > estimated anatomical dead space) was higher (87.9% vs.21.9%; P < 0.01) and the median Vte was larger (6.9 ml/kg vs. 0 ml/kg; P < 0.01) with nCPAP than that with FmCPAP. Application of CPAP prior to induction of general anesthesia did not affect Vte in both approaches (nCPAP pre- vs. post; 7.9 ml/kg vs. 5.8 ml/kg, P = 0.07) (FmCPAP pre- vs. post; 0 ml/kg vs. 0 ml/kg, P = 0.11). nCPAP produced more effective tidal volume than FmCPAP in unconscious subjects.Trial registration: Clinical, Identifier: NCT01524614.
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    Revista espanola de anestesiologia y reanimacion 58(6):384-6.
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    Anesthesia and analgesia 12/2009; 109(6):1723-5. DOI:10.1213/ANE.0b013e3181b6e9ce · 3.47 Impact Factor
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